PRW 1830211 Xtreme Duty SFI-Rated External Balance 164 Teeth Steel Flexplate for Ford 289-351W 1963-82 Engineered to handle extreme duty applications Designed to take the punishment of todays high horsepower engines 4mm thick centerplate provides a solid foundation Ring gears are precision welded to meet SFI specifications, utilizing robotic machinery and cold-welding process